1. Field of the Invention
The present invention relates to a portable automatic dialing unit, and more specifically, it relates to a portable automatic dialing unit which converts previously registered data to corresponding tones and outputs the same from a speaker, so that the tones are transmitted to a telephone line to drive a telephone switchboard.
2. Description of the Prior Art
In order to make a telephone call, it has been generally necessary to dial a target telephone number or input a password. However, with recent development of telephone service, digits of such dialing have increased to cause complications in dialing. Further, it is difficult to keep a lot of telephone numbers in mind.
There has recently been proposed a portable automatic dialing unit, which has a storage function for serving as a telephone directory and a function of automatically transmitting tones. This portable automatic dialing unit comprises a key manipulation part and a display, similarly to the so-called electronic calculator. The key manipulation part includes various keys for inputting and retrieving data. Telephone numbers and data for retrieving the same, such as personal names, are inputted through the key manipulation part and stored in an internal memory such as a RAM, for example. In order to make a telephone call, the user manipulates a retrieval key provided in the key manipulation part, so that a corresponding telephone number is read from the memory and displayed on the display. The user further presses a key for transmitting tones, so that data of the retrieved telephone number is converted to corresponding tone signals. The tone signals are audio frequency signals having the same frequencies as tone signals transmitted to a telephone line through pushbutton manipulation in the so-called pushbutton dialing telephone set. The tone signals are supplied to an internally provided speaker, and outputted to the exterior as tones. At this time, the portable automatic dialing unit is attached to the mouthpiece of a telephone receiver, so that the tone signals are transmitted to a telephone line through the telephone receiver. The tone signals, which are audio frequency signals of the same frequencies as those of a pushbutton dialing telephone set as hereinabove described, drives a telephone switchboard to connect the telephone line to another telephone set having the number corresponding to the tone signals. Thus, the portable automatic dialing unit is extremely convenient since the same requires no dialing operation and can store a lot of telephone numbers and data relating to the same.
In recent years, a variety of special telephone service is carried out in addition to general service for telephone communication. In order to use such special telephone service, it is necessary to transmit various dial data such as an access code of a telephone company, a password etc., in addition to a target telephone number. A conventional portable automatic dialing unit has an SSN (Special Service Number) function of registering, retrieving and automatically transmitting dial data required for such special telephone service, in addition to a function of registering, retrieving and automatically transmitting data of general telephone numbers.
FIGS. 1(a) and 1(b) shows SSN functions in conventional portable automatic dialing units. As shown in FIGS. 1(a) and (b), the conventional portable automatic dialing units have SSN functions of the following two types:
(1) transmitting a target telephone number following a number registered in an SSN mode; and
(2) previously transmitting a target telephone number and thereafter transmitting a number registered in the SSN mode.
On the other hand, recently there has been the need that a target telephone number must be inserted in dial data for special telephone service, in order to use such special telephone service. However, the conventional portable automatic dialing unit cannot cope with such case since the dial data for special telephone service can merely precede or follow the target telephone number according to its SSN function.
In order to make a long-distance call through the public telephone system in the U.S., it is necessary to add an identification number "1" to the head of a target telephone number to indicate that this is a long-distance call. Further, there is special telephone service called calling card dialing service in the U.S. In this calling card dialing service, a telephone company issues a calling card (a kind of a credit card relating to telephone) to a customer. A calling card number allocated to each customer is recorded in this calling card. The customer dials this calling card number following a target telephone number, so that the charge for the current telephone call is automatically paid from the customer's bank account. Through such calling card service, therefore, the customer can make a telephone call from a public telephone in Los Angeles to New York, for example, with no coins. The telephone charges are billed monthly in a single sum.
At present, some of public telephones are provided with card readers, while others generally have no such card readers. In the former case, the card reader can read a calling card number to automatically transmit the same to a center. Thus, it is not necessary to dial the calling card number. In a general public telephone having no such card reader, on the other hand, the user must dial his calling card number following a target telephone number. While the way of making a telephone call through such calling card service is slightly varied with telephone companies, an identification number "0" for the calling card service must be added to the head of the target telephone number in any case, whether it is a long-distance call or a local call. In order to make a long-distance call through the calling card service, therefore, the identification number "0" must be added to the head of the target telephone number in place of the identification number "1" in the case of the aforementioned general long-distance call.
However, a conventional portable automatic dialing unit cannot cope with such replacement of the identification numbers "1" and "0". Therefore, only target telephone numbers are stored in the unit and the user manually dials "1" at the head for making a general long-distance call, while manually dialing "0" at the head and the card number at the end for making a long-distance call through calling card service. Thus, the conventional portable automatic dialing unit still requires troublesome dialing operation in the case of a long-distance call.